It is known to provide at least one opening in the wall of the nut which leads to the inner side thereof. A redirecting portion or piece which includes a redirecting or ball recirculating channel for returning balls, running in thread grooves of the screw and the nut, is located in the opening. The redirecting channel of the redirecting piece opens into at least one thread groove of the nut and has associated with it an abutment shoulder for the balls, which protrudes into this thread groove.
A ball screw with these features is known, for example, from German Patent 2,355,844. The redirecting piece is made of a plastics material and contains a substantially U-shaped redirecting channel joining two adjacent thread grooves of the nut. It is inserted from the inside into a continuous, cylindrical bore in the wall of the nut. The redirecting piece is provided with a projection which fits into a corresponding recess in the screw nut in order to position and fix it correctly. To ensure silent operation of the ball screw, measures must be taken to prevent both the redirecting channel itself and the region in which it opens into the thread grooves of the nut and the screw from having any abrupt transitions or other irregularities which would impair the quiet running of the balls. Therefore, in view of the manufacturing tolerances, the prefabricated redirecting pieces have to be adapted to the bore in the wall of the nut and adjusted in relation to the screw, and subsequent machining, for example, grinding is additionally required during assembly.
The same applies in principle to ball screws wherein the ball-redirecting pieces inserted in corresponding openings in the wall of the nut delimit only parts of the ball-redirecting channel which is continued through a bore in the wall of the nut (see, for example, German Patent Disclosure Document DE-OS 1,923,742). Here additional care must be taken to ensure that there are no undesired abrupt transitions at the point where the redirecting pieces join the redirecting channel bore in the wall of the nut, which similarly result in noise and premature wear.